http://blogs.msdn.com/b/jackgr/archive/2010/04/19/silverlight-clients-and-appfabric-access-control.aspxThe Silverlight behavior is designed to prevent cross site attacks in which request headers on a POST could be redirected to unknown domains. Clearly, this is preferable to the .NET framework behavior, which puts the client at risk. However, the HTTPen-USTelligent Evolution Platform Developer Build (Build: 5.6.50428.7875)